Preliminary Design and Neutronics Analysis for a Medium Temperature Heat Pipe Cooled Reactor

Traditional heat pipe cooled reactors have the characteristics of high core temperature and high fuel enrichment, which makes its development limited by several unfavorable factors, such as the limitation of high temperature materials and low burnup, etc. In this paper, a new heat pipe cooled reactor with a rated thermal power of 1.5MWt is proposed to address the problems of high operating temperature and high fuel enrichment. Low-enriched uranium is used as fuel. Mercury heat pipe is used instead of the traditional high temperature heat pipe in order to maintain a low operating temperature of around 350 °C. A superheated steam/water cycle with an efficiency of 33% can ensure the high thermal efficiency of the reactor. The Monte Carlo software MCNP5 is used to analyze the core physics characteristics, including the control rod worth, neutron energy spectrum, neutron distribution, temperature coefficient and core lifetime. A radial power peaking factor of 1.46 with controls inserted can satisfy the heat transfer requirements. A high control rod worth and high transient negative temperature coefficient can also ensure a high inherent safety of this reactor. The core lifetime is around 8 years.